local url = "http://justus.l--n.de:3000/JUFS/cc_housebuild/raw/branch/main/src/main.lua"

if not _G["turtle"] then
    error("This program only runs on turtles!")
end

local turtle = _G["turtle"]

print("House building system")
print("JUFS Technologies (c) 2026 (Justus Wolff)")

print("fuel: "..tostring(turtle.getFuelLevel()).."/"..tostring(turtle.getFuelLimit()))
os.sleep(0.1)

function term.setcol(fc, bc)
    term.setTextColor(fc)
    term.setBackgroundColor(bc)
end
local function reset()
    term.setcol(colors.white, colors.black)
    term.clear()
    term.setCursorPos(1,1)
end
local function incline()
    local _,y = term.getCursorPos()
    term.setCursorPos(1,y+1)
end
local function selopt(options, title)
    local selected = 1

    while true do
        reset()
        term.setcol(colors.black, colors.white)
        term.write(title)
        for i,v in pairs(options) do
            incline()
            if i == selected then
                term.setcol(colors.black, colors.blue)
            else
                term.setcol(colors.white, colors.black)
            end
            term.write(v)
        end

        local event,key = os.pullEvent("key")
        if keys.getName(key) == "w" and selected ~= 1 then
            selected = selected - 1
        end
        if keys.getName(key) == "s" and selected ~= #options then
            selected = selected + 1
        end
        if keys.getName(key) == "enter" then
            return selected
        end
    end
end
local function integritycheck()
    if not fs.exists("designs") then
        fs.makeDir("designs")
    end
end
local function posasstring(...)
    local positions = {...}
    local out = ""
    for _,v in pairs(positions) do
        out = out .. tostring(v) .. ":"
    end
    return out
end
local function load(name)
    local file = fs.open("designs/"..name, "r")
    local content = file.readAll()
    file.close()
    content = textutils.unserialiseJSON(content)
    return content["buf"],content["dimensions"]
end
local function bufistype(buf, x,y,z, targettype)
    if buf[posasstring(x,y,z)] == targettype then
        return true
    else
        return targettype == 0 and buf[posasstring(x,y,z)] == nil
    end
end
local function fill_getneighbors(x,y,z, sx,sz, seltype,buf)
    local out = {}
    if x ~= sx and bufistype(buf, x+1,y,z, seltype) then table.insert(out, {x+1,z}) end
    if x ~= 1 and bufistype(buf, x-1,y,z, seltype) then table.insert(out, {x-1,z}) end
    if z ~= sz and bufistype(buf, x,y,z+1, seltype) then table.insert(out, {x,z+1}) end
    if z ~= 1 and bufistype(buf, x,y,z-1, seltype) then table.insert(out, {x,z-1}) end
    return out
end
local function fill(ntype, x,y,z, buf, sx,sz)
    local inittype = buf[posasstring(x,y,z)]
    if inittype == ntype then return end -- no work needs to be done

    local neighbors = fill_getneighbors(x,y,z, sx,sz, inittype,buf)
    buf[posasstring(x,y,z)] = ntype
    local processed = 0
    local totalneighbors = #neighbors
    term.setcol(colors.white, colors.black)
    while #neighbors > 0 do
        term.setCursorPos(1,1)
        term.write(tostring(processed).."/"..tostring(totalneighbors))
        local cn = table.remove(neighbors, 1)
        local cx,cz = cn[1],cn[2]
        local newneigh = fill_getneighbors(cx,y,cz, sx,sz, inittype,buf)
        for _,v in pairs(newneigh) do
            table.insert(neighbors, v)
            buf[posasstring(v[1],y,v[2])] = ntype
            totalneighbors = totalneighbors + 1
        end
        buf[posasstring(cx,y,cz)] = ntype
        processed = processed + 1
    end
end
local function newdesign()
    local buf = {}
    local dimensions = {
        x = 8,
        z = 8,
        y = 1
    }
    local currentfloor = 1
    local camx,camy = 0,0
    local currentblock = 2
    local blockindex = 1
    local blocks = {
        2, -- no ceiling
        3, -- doorway
        4, -- glass
    }
    local function renderblock(index)
        local block = blocks[index]
        if block == 2 then -- no ceiling
            term.blit("C", colors.toBlit(colors.black), colors.toBlit(colors.red))
        end
        if block == 3 then -- doorway
            term.blit("D", colors.toBlit(colors.black), colors.toBlit(colors.brown))
        end
        if block == 4 then -- glass
            term.blit("W", colors.toBlit(colors.black), colors.toBlit(colors.white))
        end
    end
    local shift = false

    while true do
        -- render buf
        reset()
        for x=1+camx,dimensions["x"]+camx,1 do
            for z=1+camy,dimensions["z"]+camy,1 do
                local currentbuf = buf[posasstring(x-camx, currentfloor, z-camy)]
                term.setCursorPos(x, z)
                if currentbuf == 1 then -- wall
                    term.blit(" ", colors.toBlit(colors.white), colors.toBlit(colors.white))
                elseif currentbuf and currentbuf > 1 then -- blocks
                    renderblock(currentbuf-1)
                    --term.blit("C", colors.toBlit(colors.black), colors.toBlit(colors.red))
                elseif currentbuf == 0 or currentbuf == nil then -- nothing
                    if buf[posasstring(x-camx, currentfloor-1, z-camy)] == 2 then
                        term.blit("\127", colors.toBlit(colors.red), colors.toBlit(colors.black))
                    else
                        term.blit("\127", colors.toBlit(colors.gray), colors.toBlit(colors.black))
                    end
                end
            end
        end
        term.setcol(colors.yellow, colors.black)
        local _,y = term.getSize()
        term.setCursorPos(1,y-1)
        term.write("Press Ctrl for menu. ")
        term.setCursorPos(1,y)
        term.write("x: "..tostring(camx))
        term.write(" z: "..tostring(camy))
        term.write(" floor: "..tostring(currentfloor))
        term.write(" Block: ")
        renderblock(blockindex)

        -- user input
        local event = table.pack(os.pullEvent())
        if event[1] == "mouse_click" or event[1] == "mouse_drag" then
            event[3] = event[3]-camx
            event[4] = event[4]-camy
            if event[3] <= dimensions["x"] and event[4] <= dimensions["z"] then
                if event[2] == 1 then -- left button, set
                    if shift then
                        fill(1, event[3],currentfloor,event[4], buf,dimensions["x"],dimensions["z"])
                    end
                    buf[posasstring(event[3], currentfloor, event[4])] = 1
                end
                if event[2] == 3 then -- middle button, set special block
                    if shift then
                        fill(currentblock, event[3],currentfloor,event[4], buf,dimensions["x"],dimensions["z"])
                    end
                    buf[posasstring(event[3], currentfloor, event[4])] = currentblock
                end
                if event[2] == 2 then -- right button, erase
                    if shift then
                        fill(0, event[3],currentfloor,event[4], buf,dimensions["x"],dimensions["z"])
                    end
                    buf[posasstring(event[3], currentfloor, event[4])] = 0
                end
            end
        end
        if event[1] == "mouse_scroll" then
            if event[2] == 1 then -- down
                if blockindex == #blocks then blockindex = 1 else blockindex = blockindex + 1 end
            end
            if event[2] == -1 then -- up
                if blockindex == 1 then blockindex = #blocks else blockindex = blockindex - 1 end
            end
            currentblock = blocks[blockindex]
        end
        if event[1] == "key" then
            if keys.getName(event[2]) == "leftShift" then
                shift = true
            end
            if keys.getName(event[2]) == "leftCtrl" then -- menu
                local action = selopt({
                    "Save",
                    "Load",
                    "Exit",
                    "Change X size",
                    "Change floor amount",
                    "Change Z size"
                }, "menu")
                if action == 3 then return end -- exit
                if action == 1 then -- save
                    reset()
                    for _,v in pairs(fs.list("designs")) do
                        term.write(v)
                        incline()
                    end
                    write("Enter name: ")
                    local name = read()
                    local file = fs.open("designs/"..name, "w")
                    file.write(textutils.serialiseJSON({
                        ["dimensions"] = dimensions,
                        ["buf"] = buf
                    }))
                    file.close()
                end
                if action == 2 then -- load
                    reset()
                    for _,v in pairs(fs.list("designs")) do
                        term.write(v)
                        incline()
                    end
                    write("Enter name: ")
                    local name = read()
                    if not fs.exists("designs/"..name) or name == "" then
                        printError("Design not found!")
                    else
                        buf,dimensions = load(name)
                        camx,camy,currentfloor = 0,0,1
                    end
                end
                if action == 4 then -- change X size
                    reset()
                    write("Enter new X size: ")
                    local xsize = tonumber(read())
                    dimensions["x"] = xsize
                end
                if action == 5 then -- change floor amount
                    reset()
                    write("Enter new floor amount: ")
                    local ysize = tonumber(read())
                    dimensions["y"] = ysize
                end
                if action == 6 then -- change Z size
                    reset()
                    write("Enter new Z size: ")
                    local zsize = tonumber(read())
                    dimensions["z"] = zsize
                end
            end
            if keys.getName(event[2]) == "q" and currentfloor < dimensions["y"] then -- go up
                currentfloor = currentfloor + 1
            end
            if keys.getName(event[2]) == "e" and currentfloor > 1 then -- go down
                currentfloor = currentfloor - 1
            end
            if keys.getName(event[2]) == "w" and camy < dimensions["z"] then -- pan up
                camy = camy + 1
            end
            if keys.getName(event[2]) == "s" and camy > -dimensions["z"] then -- pan down
                camy = camy - 1
            end
            if keys.getName(event[2]) == "a" and camx < dimensions["x"] then -- pan left
                camx = camx + 1
            end
            if keys.getName(event[2]) == "d" and camx > -dimensions["z"] then -- pan right
                camx = camx - 1
            end
        end
        if event[1] == "key_up" then
            if keys.getName(event[2]) == "leftShift" then shift = false end
        end
    end
end
local function move(direction, continousattempt)
    if direction == "left" then
        turtle.turnLeft()
        return
    end
    if direction == "right" then
        turtle.turnRight()
        return
    end
    while true do
        if turtle.getFuelLevel() == 0 then
            reset()
            print("Out of fuel! Please insert fuel into current slot.")
            while true do
                local suc = turtle.refuel(64)
                if suc then
                    print("Refuelled. Press enter to continue.")
                    read("")
                    break
                end
                os.sleep(1)
            end
        end
        local suc,reason = turtle[direction]()
        if not suc and not continousattempt then
            printError(reason)
            print("Resolve the error and press enter to continue.")
            read("")
        elseif suc then
            break
        end
    end
end
local function place(direction)
    local func = turtle.place
    local cfunc = turtle.compare
    if direction == "down" then
        func = turtle.placeDown
        cfunc = turtle.compareDown
    end
    if direction == "up" then
        func = turtle.placeUp
        cfunc = turtle.compareUp
    end

    while true do
        local suc = func()
        if not suc then -- next slot
            if cfunc() and turtle.getItemDetail(turtle.getSelectedSlot()) ~= nil then return end
            local current = turtle.getSelectedSlot()
            if current == 16 then
                turtle.select(1)
            else
                turtle.select(current+1)
            end
        else break end
        os.sleep(0) -- yield
    end
end
local function placebuf(buf, x, y, z)
    if buf[posasstring(x,y,z)] == 1 then
        place("down")
    end
end
local function directiondist(direction, wanted)
    if direction == 0 then return 1 end
    if direction == 1 and wanted == -1 then return 2 end
    if direction == -1 and wanted == 1 then return 2 end

    if direction ~= wanted then return 1 end -- failsafes
    if direction == wanted then return 0 end
end
local function needstobeplaced(placecode, clayer)
    if clayer == 0 or clayer == 2 then
        return placecode == 1
    end
    if clayer == 1 then
        return placecode == 1 or placecode == 4
    end
    if clayer == 3 then
        return placecode == 1 or placecode == 4 or placecode == 3
    end
end
local function getnearestunplaced(buf, pbuf, cx,cy,cz,clayer, sx,sz, direction)
    local distance = math.huge
    local selected = nil

    for x=1,sx,1 do
        for y=1,sz,1 do
            local extracost = 0
            if x ~= cx and direction ~= 0 then
                extracost = extracost + 1
            end
            if y > cz and direction ~= 1 then
                extracost = extracost + directiondist(direction, 1)
            end
            if y < cz and direction ~= -1 then
                extracost = extracost + directiondist(direction, -1)
            end

            local needplace = buf[posasstring(x,cy,y)]
            if pbuf[posasstring(x,cy,y)] then needplace = 0 end -- already placed
            needplace = needstobeplaced(needplace, clayer)
            if needplace then -- needs to be placed, calculate distance
                local cd = math.abs(y-cz)+math.abs(x-cx) -- raw distance (amount of blocks between)
                cd = cd + extracost
                if cd < distance then
                    distance = cd
                    selected = {x,y}
                end
            end
        end
    end
    return selected
end
local function center(direction, wanted)
    if direction == 1 and wanted ~= 1 then
        move("left")
        return true
    end
    if direction == -1 and wanted ~= -1 then
        move("right")
        return true
    end
    if direction == 0 then return true end
    return false
end
local function moveto(x,y,cx,cz,direction)
    while x ~= cx do
        if cx < x then -- x
            center(direction)
            direction = 0
            cx = cx + 1
            move("forward")
        end
        if cx > x then
            center(direction)
            direction = 0
            cx = cx - 1
            move("back")
        end
    end
    while y ~= cz do
        if y > cz then -- z
            if center(direction, 1) then move("right") end
            cz = cz + 1
            move("forward")
            direction = 1
        end
        if y < cz then
            if center(direction, -1) then move("left") end
            cz = cz - 1
            move("forward")
            direction = -1
        end
    end
    return cx,cz,direction
end
local function tcontains(x, y)
    for _,v in pairs(x) do
        if v == y then return true end
    end
    return false
end
local function render(buf, pbuf, cx,cy,cz, tx,tz, sx,sz, shouldsetlist,invertslist)
    shouldsetlist = shouldsetlist or {
        1,
    }

    local tsx,tsy = term.getSize()
    local camx,camy = cx-(tsx/2),cz-(tsy/2)

    reset()
    for x=1,sx,1 do
        for z=1,sz,1 do
            local currentbuf = pbuf[posasstring(x, cy, z)]
            term.setCursorPos(x-camx, z-camy)
            if currentbuf then -- wall
                term.blit(" ", colors.toBlit(colors.white), colors.toBlit(colors.white))
            elseif (currentbuf == false or currentbuf == nil) and (invertslist and not tcontains(shouldsetlist, buf[posasstring(x, cy, z)]) or tcontains(shouldsetlist, buf[posasstring(x, cy, z)])) then -- nothing
                term.blit("\127", colors.toBlit(colors.gray), colors.toBlit(colors.black))
            end
        end
    end
    term.setCursorPos(cx-camx,cz-camy)
    term.blit(" ", colors.toBlit(colors.red), colors.toBlit(colors.red))
    term.setCursorPos(tx-camx,tz-camy)
    term.blit(" ", colors.toBlit(colors.lime), colors.toBlit(colors.lime))
end
local function printdes(buf, dimensions)
    move("up")
    move("forward")

    local cx = 1
    local cz = 1
    local direction = 0
    for cy=1,dimensions["y"],1 do
        local setlists = {
            {1,4},
            {1},
            {1,3,4},
        }
        for clayer=1,3,1 do -- build walls
            local pbuf = {}
            while true do
                local target = getnearestunplaced(buf, pbuf, cx,cy,cz,clayer, dimensions["x"],dimensions["z"], direction)
                if not target then break end

                render(buf, pbuf, cx,cy,cz, target[1],target[2], dimensions["x"],dimensions["z"], setlists[clayer])

                --read("")

                cx,cz,direction = moveto(target[1],target[2],cx,cz,direction)
                place("down")
                pbuf[posasstring(cx,cy,cz)] = true
            end
            move("up")
        end
        -- build ceiling/floor
        local pbuf = {}
        local cbuf = {}
        for _cz=1,dimensions["z"],1 do
            for _cx=1,dimensions["x"],1 do
                if buf[posasstring(_cx,cy,_cz)] ~= 2 then
                    cbuf[posasstring(_cx,0,_cz)] = 1
                else
                    cbuf[posasstring(_cx,0,_cz)] = 0
                end
            end
        end
        while true do
            local target = getnearestunplaced(cbuf, pbuf, cx,0,cz,0, dimensions["x"],dimensions["z"], direction)
            if not target then break end

            render(cbuf, pbuf, cx,0,cz, target[1],target[2], dimensions["x"],dimensions["z"], {1})

            cx,cz,direction = moveto(target[1],target[2],cx,cz,direction)
            place("down")
            pbuf[posasstring(cx,0,cz)] = true
        end
        -- return to standard pos but +1 to y
        cx,cz,direction = moveto(1,1,cx,cz,direction)
        move("up")
    end
    cx,cz,direction = moveto(0,1, cx,cz, direction)
    for _=1,dimensions["y"]*(4)+1,1 do -- go back to starting position
        move("down")
    end
    center(direction)
end

-- vertical stack printing
local function VP_movetoy(y, target)
    while y > target do
        move("down", true)
        y = y - 1
    end
    while y < target do
        move("up", true)
        y = y + 1
    end
    return target
end
local function VP_moveto(x,z, cx,cz,direction)
    local y = 0
    --[[
    y lanes for directions:
    1: +x
    2: -x
    3: +z
    4: -z
    ]]--
    while x ~= cx do
        if cx < x then -- x
            center(direction)
            direction = 0
            y = VP_movetoy(y, 1)
            cx = cx + 1
            move("forward", true)
        end
        if cx > x then
            center(direction)
            direction = 0
            y = VP_movetoy(y, 2)
            cx = cx - 1
            move("back", true)
        end
    end
    while z ~= cz do
        if z > cz then -- z
            if center(direction, 1) then move("right") end
            y = VP_movetoy(y, 3)
            cz = cz + 1
            move("forward", true)
            direction = 1
        end
        if z < cz then
            if center(direction, -1) then move("left") end
            y = VP_movetoy(y, 4)
            cz = cz - 1
            move("forward", true)
            direction = -1
        end
    end
    VP_movetoy(y, 0)
    return cx,cz,direction
end
local function VP_optimizestack(target)
    -- go from top to bottom and erase false entries until we encounter a true one.
    local index = #target
    while #target > 0 do
        if target[index] then break else
            table.remove(target, index)
            index = index - 1
        end
    end

    return target
end
local function VP_createstack(buf, dimensions)
    local fout = {
        ["height"] = dimensions["y"]*(4)+1,
        ["dimensions"] = dimensions,
    }
    local out = {}


    for x=1,dimensions["x"],1 do
        for z=1,dimensions["z"],1 do

            local tempbuf = {}
            for y=1,dimensions["y"],1 do -- for each y dimension
                local placecode = buf[posasstring(x,y,z)]
                for layer=1,3,1 do -- layers
                    table.insert(tempbuf, needstobeplaced(placecode, layer))
                end
                -- ceiling
                table.insert(tempbuf, buf[posasstring(x,y,z)] ~= 2)
            end
            VP_optimizestack(tempbuf)

            if #tempbuf > 0 then
                out[posasstring(x,z)] = tempbuf
            end
        end
    end


    fout["stacks"] = out
    return fout
end
local function VP_lengthofdict(target)
    local out = 0
    for _,v in pairs(target) do out = out + 1 end
    return out
end
local function VP_splitstack(_stack, x)
    local stack = _stack["stacks"]
    local dimensions = _stack["dimensions"]
    local sx = dimensions["x"]
    local sz = dimensions["z"]
    local height = _stack["height"]
    local stacks = {}
    local unevenstack = {}
    local stackmod = math.fmod(VP_lengthofdict(stack), x)
    local stackdiv = math.floor(VP_lengthofdict(stack)/x)

    if stackmod ~= 0 then
        for tempstackindex=0,stackmod,1 do
            unevenstack[posasstring(math.fmod(tempstackindex, sx),math.floor(tempstackindex/sx))] = stack[posasstring(math.fmod(tempstackindex, sx),math.floor(tempstackindex/sx))]
        end
    end

    if stackdiv ~= 0 then
        local eind = 0
        local x2 = x
        if stackmod ~= 0 then x2 = x - 1 end
        for _=0,x2,1 do
            local buf = {}
            for stackind=eind,stackdiv+eind,1 do
                buf[posasstring(math.fmod(stackind, sx),math.floor(stackind/sx))] = stack[posasstring(math.fmod(stackind, sx),math.floor(stackind/sx))]
            end
            table.insert(stacks, buf)
            eind = eind + stackdiv
        end
    end

    local out = {
        height=height,
        stacks={}
    }
    if #unevenstack > 0 then table.insert(out["stacks"],unevenstack) end
    for _,v in pairs(stacks) do
        table.insert(out["stacks"],v)
    end
    return out
end
--[[local function VP_inspectsplitted(stacks, dimensions) -- I will probably never finish this.
    local currentselected = 1

    while true do
        reset() -- render
        local _,y = term.getSize()
        term.setCursorPos(1,y)
        term.setcol(colors.yellow, colors.black)
        term.write("Currentlayer: ")
        term.write(tostring(currentselected))

        local event = table.pack(os.pullEvent())
        if event[1] == "key" then
            
        end
    end
end]]
local function VP_printstack(buf, dimensions, cx,cy,cz,direction)
    reset()
    move("up")
    for _=1,buf["height"]-cy,1 do
        move("up")
    end
    local ox,oz = cx,cz
    cx,cz,direction = VP_moveto(cx+1,cz, cx,cz,direction)

    for x=1,dimensions["x"],1 do
        for z=1,dimensions["z"],1 do

            local tempbuf = buf["stacks"][posasstring(x,z)]
            if tempbuf then
                cx,cz,direction = VP_moveto(x,z, cx,cz,direction)
                for _=1,buf["height"],1 do
                    move("down")
                end
                for _,v in pairs(tempbuf) do
                    if v then
                        place("down")
                    end
                    move("up")
                end
                move("up")
            end
        end
    end
    VP_moveto(ox,oz, cx,cz,direction)
    for _=1,buf["height"],1 do
        move("down")
    end
    return cx,cz,direction
end
local function VP_calccost(stacks, height,sx,sz) -- calculate needed blocks
    local cost = 0
    for cx=1,sx,1 do
        for cz=1,sz,1 do

            local tempbuf = stacks[posasstring(cx,cz)]
            if tempbuf then
                for ind=1,height,1 do
                    if tempbuf[ind] then cost = cost + 1 end
                end
            end

        end
    end
    return cost
end
local function VP_selectpos(design,dimensions,msg, cx,cz)
    cx,cz = cx or 0, cz or 0
    local camx,camz = cx,cz
    while true do
        render(design,{}, camx,1,camz, camx,camz, dimensions["x"],dimensions["z"], {1,4})
        term.setCursorPos(1,1)
        term.write(msg)
        local _,y = term.getSize()
        term.setCursorPos(1,y)
        term.write("x: ")
        term.write(tostring(camx))
        term.write(" z: ")
        term.write(tostring(camz))

        local _,key = os.pullEvent("key")
        key = keys.getName(key)
        if key == "w" then
            camz = camz - 1
        end
        if key == "s" then
            camz = camz + 1
        end
        if key == "a" then
            camx = camx - 1
        end
        if key == "d" then
            camx = camx + 1
        end
        if key == "enter" then
            break
        end
    end
    return camx,camz
end

local function expwarn()
    reset()
    term.write("This mode is experimental! Be cautious!")
    incline()
    term.write("Enter to continue.")
    read("")
end
local function randomstr(length)
    local possible = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
    local out = ""
    for _=1,length,1 do
        local ind = math.random(#possible)
        out = out .. string.sub(possible, ind, ind)
    end
    return out
end

while true do
    integritycheck()
    local action = selopt({
        "New Design",
        "Print Design",
        "VPrint Design",
        "Join VPrint",
        "Update",
    }, "Select Action")

    if action == 1 then
        newdesign()
    end
    if action == 2 then
        reset()
        for _,v in pairs(fs.list("designs")) do
            term.write(v)
            incline()
        end
        write("Enter name: ")
        local name = read()
        if not fs.exists("designs/"..name) or name == "" then
            printError("Design not found!")
        else
            local buf,dimensions = load(name)
            write("Calculating fuel cost...")
            local cost = dimensions["x"]*dimensions["z"]*(dimensions["y"]*4-1)
            print(tostring(turtle.getFuelLevel()).."/"..tostring(cost))
            if turtle.getFuelLevel() < cost then
                write("WARNING: Not enough fuel! Continue anyway? y/n: ")
                while true do
                    local ans = read("")
                    if ans == "y" then
                        printdes(buf, dimensions)
                        break
                    elseif ans == "n" then break end
                end
            else
                printdes(buf, dimensions)
            end
        end
    end
    if action == 3 then
        expwarn()

        peripheral.find("modem", rednet.open)
        reset()
        for _,v in pairs(fs.list("designs")) do
            term.write(v)
            incline()
        end
        write("Enter name: ")
        local name = read()
        if not fs.exists("designs/"..name) or name == "" then
            printError("Design not found!")
        else
            local buf,dimensions = load(name)
            local stacks = VP_createstack(buf, dimensions)
            local height = stacks["height"]
            print("Stacks created.")
            local code = randomstr(5)
            print("Pair code: '"..code.."'")

            write("Enter amount of partaking turtles: ")
            local expam = tonumber(read())

            write("Press enter to send pair request.")
            read("")
            rednet.broadcast({
                code=code,
            }, "HB_vprint_pair")
            print("Sent. awaiting pair accepts.")
            local accepted = {}
            while #accepted < expam do
                local id,msg = rednet.receive("HB_vprint_pairespond")
                if msg["code"] == code then
                    table.insert(accepted, id)
                    reset()
                    term.write(tostring(#accepted).."/"..tostring(expam))
                end
            end

            reset()
            print("Paired. Splitting stacks and sending out...")
            stacks = VP_splitstack(stacks, #accepted+1) -- plus 1 because we also build as the master turtle.
            if #stacks["stacks"] ~= #accepted+1 then
                printError("Internal error with VP_splitstack. It returned "..#stacks["stacks"].." stacks.")
                return
            end
            for i,v in pairs(accepted) do
                reset()
                print("ID "..tostring(v).." needs "..VP_calccost(stacks["stacks"][i], stacks["height"],dimensions["x"],dimensions["z"]).." blocks.")
                print("Please ensure that turtle has that many blocks and press enter to continue.")
                read("")
                rednet.send(v, {
                    stack=stacks["stacks"][i],
                    dimensions=dimensions,
                    height=height
                }, "HB_vprint_pairacknowledge")
            end

            print("This turtle needs "..tostring(VP_calccost(stacks["stacks"][expam+1], stacks["height"],dimensions["x"],dimensions["z"])).." blocks.")
            print("Please ensure that turtle has that many blocks and press enter to continue.")
            read("")

            local x,y = 0,0
            for _,v in pairs(accepted) do
                x,y = VP_selectpos(buf,dimensions,"Select position of turtle "..tostring(v), x,y)
                rednet.send(v, {
                    cx=x,
                    cz=y,
                }, "HB_vprint_pairpossend")
            end
            reset()
            write("Ready to begin, press enter to continue")
            read("")
            print("Sending begin signal.")
            for _,v in pairs(accepted) do
                rednet.send(v, {}, "HB_vprint_begin")
            end

            local ownstack = {
                stacks=stacks["stacks"][expam+1],
                dimensions=dimensions,
                height=height
            }
            VP_printstack(ownstack,dimensions, 0,0,1,0)
        end
    end
    if action == 4 then
        expwarn()

        peripheral.find("modem", rednet.open)
        reset()
        term.write("Enter the code: ")
        local code = read()
        local masterid = 0
        local buf = {}
        local dimensions = {}
        local height = 0
        local cx,cz = 0,0

        while true do -- await pairing request and respond
            local id,request = rednet.receive("HB_vprint_pair")
            if request["code"] == code then
                masterid = id
                print("Detected master: "..tostring(masterid))
                print("Responding...")
                rednet.send(masterid, {
                    code=code,
                }, "HB_vprint_pairespond")
                print("Waiting for response... ID: "..tostring(os.getComputerID()))
                local id,msg = -1,{}
                repeat
                    id,msg = rednet.receive("HB_vprint_pairacknowledge")
                until id == masterid
                buf = msg["stack"]
                dimensions = msg["dimensions"]
                height = msg["height"]
                break
            end
        end
        print("Received stacks and dimensions. ID: "..tostring(os.getComputerID()))
        local id,msg = -1,"" -- wait until we get our current position
        repeat
            id,msg = rednet.receive("HB_vprint_pairpossend")
        until id == masterid
        cx,cz = msg["cx"],msg["cz"]

        repeat -- wait until we can begin
            id = rednet.receive("HB_vprint_begin")
        until id == masterid

        local ownstack = {
            stacks=buf,
            dimensions=dimensions,
            height=height
        }
        VP_printstack(ownstack,dimensions, cx,0,cz,0)
    end
    if action == 5 then
        shell.run("rm", "main.lua")
        shell.run("wget", url)
        return
    end
end